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Don't be a LEAKY solar roof statistic! Competent installations require fore-thought and setting realistic expectations.

How to PREVENT solar panel roof pentration leaks… bolt to rafters ahead of the cure.

Prevent solar panel roof penetration leaks; this would be one of my BIGGEST hesitations going into a solar installation on my building.  Let’s DEMYSTIFY the unknown.

Installation practices vary by roof.

  • Spanish, slate style or shake roof: Things can get tricky and expensive.  Spanish and slate roof tiles can and will crack when walked upon, they require careful threading with a drill in order to insert the screw mount into the tile itself.  Tiles are fragile and easily break, so have plenty of replacements on hand.
  • Wood shake cedar shingle roof: These tiles are prone to splitting and cracking when drilled into.  They may be dry and brittle.  Again, the property owner should have extra shake tiles on hand. 
  • Composite tile roof material: Overall composite shingles are best because they’re flexible and forgiving and easy to drill through into a solid wood stud or rafter.  The solar installers will love you, and your labor cost and risk will be reduced.
  • Flat, tar-and-gravel roofs and the flat polyurethane foam roofs: This is the best case scenario because the photovoltaic modules may be aimed in any orientation or tilt desired in order to capture the sun’s rays.   Whereas, with a pitched roof, the solar installer may be limited to the orientation and tilt pre-determined by the roof.  However, if that tilt is just right, it’s going to be cheaper than tilting panels on a flat roof, because a flat roof will require constructing scaffolding to tilt the panels.


How are panels affixed to a roof?

  • Panels that are bolted to the rafters or studs: You’re safe, because panels are attached to the infrastructure of your house and not the roof.  The penetration is not made into your roofing shingle itself, but into a solid wood rafter, after which, a very high grade water tight sealant is used to seal around the penetrations and typically warranted to last 50 years.  However, it’s wise to take a yearly assessment of the sealant to check for durability.  Additionally, a great amount of solar installation labor is spent finding the exact center of the rafters. But good news here; there are new mounting products coming out that will reduce this cost substantially.
  • If you’re purchasing a NEW roof: Ask you solar installer to coordinate with your roofer so that your solar installer can come in and pre-install the solar panel posts.  Afterward, the roofer roofs, and the solar installer installs the panels.  This is the best way to avoid risk of roof penetrations altogether & reduce solar install labor cost.
  • Have a roof with existing panels? It’s about $1000 or more to temporarily remove existing panels to allow a roofer to install your roof.  Afterward, your solar company will re-install your existing solar panels.


Bottom line… we all know this:

Be a good consumer and ask questions of both the solar installer and roofer, like bonding, proof of liability insurance, check their state license for validity and any lawsuits, ask for references and interview them on their customer service experience and the current performance of their roof and solar installation.




Article written by Jennifer Coleman, Owner of Sun Source Solar Energy Brokers, Sonoma County, California.

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Contact Info

Sun Source Solar Brokers
525 East Cotati Avenue, #220
Cotati, California 94931
707-888-7046

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